textproduct: Albany

WHAT HAS CHANGED

625 AM EST Update: Temperatures were several degrees higher than the NBM this morning courtesy of pesky low-level cloud cover spanning portions of the western Mohawk Valley, eastern Catskills, Capital District, Taconics, and Berkshires. Therefore, made adjustments to the hourly temperatures over the upcoming morning hours to reflect latest obs and incorporate the latest HiRes guidance. All else remains unchanged.

243 AM EST Forecast Issuance: An additional shortwave now looks to track through the region Monday night, warranting the increase in PoPs through Tuesday morning for scattered snow showers. All else remains largely unchanged from the previous forecast issuance.

KEY MESSAGES

1) Light accumulating snow tonight through Monday morning and then again Monday night into Tuesday morning may result in slippery road and walking surfaces.

2) A prolonged period of unsettled weather remains anticipated to begin Wednesday and linger through the end of the work week, but impacts remain uncertain at this time.

DISCUSSION

KEY MESSAGE 1...

After a brief period of dry, tranquil weather today, the probability of precipitation once again increases tonight and lingers through Monday morning as two systems near the region. Guidance has remained relatively consistent in the connection of a northern- and southern-stream shortwave tonight that will ultimately drive a cyclogenetic response at the surface for a low tracking off the East Coast around the Carolinas. The northern-stream, upper-level low that is forcing the stall of the northern-stream shortwave and ultimate connection of this and its southern-stream counterpart is currently positioned over northern New Brunswick which is a bit farther north and east than what was previously forecast. While it is still forecast to sink slightly south before jetting eastward, it's now progged to track into the western Atlantic quicker than previously expected. This faster solution looks to steer the coastal low farther to the north and east tonight, rather than forcing it back towards the coast.

That said, the inverted trough about the northern periphery of the coastal low does look to extend fairly far northward, nearly meeting the Long Island Coastline. This should allow the deformation zone of the low to extend far enough north that precipitation directly associated with the coastal low will spread into our southern-most zones within the lower Mid-Hudson Valley and northwest Connecticut. The uncertainty with this forecast lies in the spatial extent of precipitation that occurs as a result of both this inverted trough and the northern-stream shortwave. Some of the latest HiRes guidance indicates a seeder-feeder response wherein moisture from the inverted trough intersects the moist CVA sector of the upper shortwave to enhance lift and therefore its moisture supply such that the separated areas of showers fill in and become more widespread. Other models indicate more of a lack of intersection of these two disturbances such that areas of showers stay separated and a horizontally-extended dry slot is observed around portions of the Eastern Catskills, Capital District, and Berkshires. But, given generally moist thermal profiles almost everywhere amid southerly flow, we increased slight chance to chance PoPs regionwide above the base NBM. And, given sub-freezing temperatures throughout the duration of shower activity, precipitation is anticipated to be in the form of snow. Generally, about 0.1" - 0.7" is anticipated across the region which could result in some slippery travel.

KEY MESSAGE 2...

Confidence continues to remain medium to high in a prolonged period of unsettled weather beginning in the middle to the end of the upcoming work week, but persistent run-to-run inconsistency maintains low confidence in system tracks, resulting precipitation types, and subsequent impacts.

Now, the previous statement may seem to contradict itself, but in reality it owes to the level of complexity with the extended period's forecast. To put it simply, we have medium to high confidence that a deamplified (predominantly zonal) flow pattern will develop across our CWA for a prolonged period of time (Tuesday through at least Sunday). This will subject us to multiple rounds of precipitation as a result of multiple upper- level shortwaves and associated surface low pressure systems that will track near or through our region during that time. This large-scale pattern has been consistently evident in the guidance for some days now, significantly increasing our confidence in its validity. But the details of the tracks of those shortwaves and low pressure systems and their resulting precipitation types are highly dependent on small scale influences that can significantly alter the impacts that we experience locally. And its in the depictions of these smaller- scale details that the guidance has consistently shown discrepancies.

The first system in the aforementioned series of systems is set to impact the region Wednesday into Thursday. Medium to high confidence exists in the development of a mid-level, cut-off low in the Northern Plains. As this low deepens, a wave of surface low pressure develops along a broad baroclinic zone (front), extending west to east towards our region. Warm air advection and potential frontogenetical forcing will increase along the boundary, allowing a stratiform precipitation shield to initiate and expand across the region as a surface wave of low pressure develops farther towards the east near the Great Lakes. The uncertainty then comes in with a few key details. The first and one of the most influential for the ultimate precipitation type is the position of the baroclinic zone. Latest ensembles, and those of the past couple of days, favor a "warmer" solution wherein the boundary is shifted farther to the north. This would place much of our region in a pseudo-warm sector and drive a predominant rain, snow, and mix thereof precipitation solution. However, there do remain outliers (~28% of ensemble members) that support a "colder" solution which keeps the boundary farther south, encompassing much of our region and making for a fairly messy precipitation solution that includes a mix of rain, snow, and freezing rain. That said, the grand ensemble, or the compilation of all ensemble members, currently supports a solution that errs more on the "warmer" side of things in that the coldest temperatures are to our north and east, but we don't quite make it into a psuedo-warm sector prior to precipitation onset. This would largely translate to a rain, snow, and mix thereof precipitation type, but could result in some isolated freezing rain especially at the onset before the warm nose reaches its full potential.

The second key detail, which will have a direct impact on the spatial extent, duration, and amount of precipitation itself, is the position of the developing surface wave. Some of the guidance now indicates the wave shifting into and traversing our area Wednesday night. This could ultimately lead to an enhancement of precipitation due to increased convergence in the lower levels and potentially a change back over to snow and/or freezing drizzle for areas that saw rain during the day Wednesday as cold air filters in on the back side of it. Other models indicate the wave staying well to our west, allowing precipitation to fizzle out as moisture and forcing is lost farther eastward away from the primary source. That said, this solution is an outlier amid the other sources of guidance and previous model runs, so we didn't put too much stock in it at this time.

For precipitation type on Wednesday, we continued to side with the NBM which kept out freezing rain potential at this time, as confidence is not high enough in its occurrence to include it in the weather forecast. Based on latest forecast thermal profiles, it is certainly not out of the realm of possibility for Wednesday, again especially at onset, as pockets of mid- and low-level dry air are hinted at which would do one of two things or a combination of both: delay precipitation reaching the surface, and/or increase the probability of a wetbulb effect where precipitation falls as snow/cloud bases are low enough that supercooled drops don't quite manifest into flakes and fall as freezing rain. But, as Wednesday is still several days away, there is plenty of time for those smaller scale details to come into better agreement, leading to greater forecast confidence. We will continue to monitor the situation closely and provide updated messaging where appropriate.

The second system during this time falls to Friday when an upper-level shortwave and surface low look to track through the Great Lakes. Similarly to Wednesday, there is medium confidence in the overall set up for Friday's system, but even more uncertainty with precipitation type and amounts given discrepancies in the exact track and strength of the system. As a result, we collaborated with our neighboring offices to maintain a mix of rain and snow for precipitation type at this time.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

Through 12z Monday...Lake-effect clouds with MVFR cigs still in place at KALB/KPSF early this morning, although satellite imagery indicating signs of the clouds slowly eroding from north to south as the flow has turned more northerly. So the clouds at KALB/KPSF should gradually scour out through around 14z-15z. High/mid level clouds will gradually increase during the day, becoming BKN-OVC between 22z-00z. A disturbance will bring a chance for -SN to the TAF sites starting around 03z-06z Monday, so will continue mention of PROB30 for possible IFR vsby with prevailing cigs lowering to MVFR levels. Winds today will be north-northeast around 4-7 kt.

Outlook...

Monday Night: Low Operational Impact. Slight Chance of SHSN. Tuesday: Low Operational Impact. Slight Chance of SHRA. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: High Operational Impact. Definite RA...SN. Wednesday Night: High Operational Impact. Definite RA...SN. Thursday: Moderate Operational Impact. Chance of RA...SN. Thursday Night: Moderate Operational Impact. Chance of RA...SN. Friday: High Operational Impact. Likely RA...SN.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.